Belt tensioner with integral damping

ABSTRACT

A belt tensioner with integral damping for use in tensioning an endless drive belt of a drive system, comprising: a housing including a pivot shaft extending along a longitudinal axis and formed with an outer axial end, and having a horizontal bottom and a circumferential wall extending vertical from the horizontal bottom, the circumferential wall having an inner circumferential wall surface and an outer circumferential wall surface, the housing being mounted rotatably fixed on said pivot shaft; a lever arm mounted pivotally on said pivot shaft and formed with a distal end and a tubular proximal end, the tubular proximal end extending into and operably connected to the housing; a spring element operatively connected to the housing and to the lever arm for pivoting the lever arm about the longitudinal axis in a belt tensioning direction; a pulley assembly mounted on the distal end of the lever arm for receiving an endless drive belt and applying a tensioning force on the endless drive belt upon pivoting the lever arm in the belt tensioning direction, the distal end having the pulley mounted thereon being spaced axially apart from the upper end of the shaft; and a damping cavity including an armplate, the armplate being mounted on the pivot shaft for providing integral damping for tensioning an endless drive belt of a drive system, the armplate comprising: (a) an armplate having a cup-shaped cavity and a plurality of spaced apart finger elements extending from the circumferential edge; and (b) a friction material on a surface of the armplate for providing at least one contact area having increased friction between the lever arm and the armplate.

FIELD OF THE INVENTION

[0001] The present invention relates to belt drive systems and,particularly to a tensioning device for power transmission belts and thelike. Specifically, the present invention relates to a tensioning devicethat is independent of the axial force on the tensioner and which willprovide improved pulley alignment and longer tensioner life.

BACKGROUND OF THE INVENTION

[0002] In the automobile industry, the various vehicle accessories suchas power steering pump, oil and air pump, air conditioner, alternator,and the like, are operated by a single endless belt driven by a pulleyconnected to the engine crankshaft. Such system is typically referred toas a “serpentine” drive belt system. To provide optimum operatingefficiency for the above-mentioned and other various accessories, it isimperative that a predetermined tensioning force be maintained on thedrive belt to insure efficient performance of the accessories as well assatisfactory service life for the belt. Because of the length of thedrive belt, there is a tendency for the belt to stretch due to wear andvibration, affecting the operating characteristics of the belt drivenaccessories. Therefore, it is conventional to use a belt tensioningdevice to provide a constant tensioning force on the belt to compensatefor the increased length of the belt due to such stretching. Referenceis made to commonly assigned U.S. Pat. Nos. 5,030,172; 5,443,424;5,545,095; 5,718,649; 5,803,850 and 6,206,797, each of which isincorporated herein by reference, for examples of prior art belttensioners.

[0003] A common type of belt tensioner embodies a stationary housing andan angular displaceable lever arm that carries a belt engaging pulley. Acoil spring is braced against the stationary housing and displaceablelever arm and biases the latter toward the belt with a tensioning forcevarying in accordance with the vibrational nature of the belt. Despitethe varying spring force, a substantially constant force acting upon thelever arm is maintained.

[0004] It is desirable that a belt tensioner be provided with a dampingmeans to prevent excessive oscillation from occurring in the springmember. Such means is designed to absorb sudden shocks and to prevent awhipping action from occurring in the tensioner and drive belt. Thisdamping means is especially critical when a coil spring is used forapplying the belt tensioning force since it is inherent to coil springsto develop natural oscillation frequencies upon applying of thefluctuating counter force by the belt. Such fluctuations diminish theefficiency of tensioning force of the spring. However, the dampingrequirements are essential in order to enable the belt system tofunction over an extended period on a pulsating machine withoutaffecting a tensioning force that acts upon the drive belt.

[0005] For example, a belt tensioning device has been proposed in U.S.Pat. No. 3,924,483 to Walker et al. wherein there is disclosed atorsional spring for pivotally moving one of the vehicle accessories toachieve the desired tensioning forces. Other tensioners of theabove-described type utilize a pair of torsional springs for pivotallymoving a lever and an idler pulley into belt tensioning engagement whichresults in an economic and compact unit. Specifically, in this type oftensioner, each spring is mounted on a respective side of the lever andengaged with the lever and housing for biasing the intervening levertoward the belt in a belt tensioning direction. Furthermore, theautomobile industry has recognized the vibrational environment of anautomobile belt system and its effect on spring oscillation.

[0006] U.S. Pat. No. 4,696,663 discloses a belt tensioner that includesa stationary housing 12, a lever arm 30, and a torsional spring 20 whichis braced against the housing and the lever and biases the lever in abelt-tensioning direction. The belt tensioner is equipped with a brake60 actuated by the spring into frictional engagement with a housing wall13. Since the torsional spring provides both the tensioning force forthe lever and the actuating brake force, the amount of damping isproportional to the belt tensioning force.

[0007] U.S. Pat. No. 4,473,362 discloses a separate damping body 108whose damping characteristics are not constant but vary proportionatelywith the position of a pivot structure 40 relative to a stationarystructure 36. A coil spring is mounted between the fixed and pivotedstructures for resiliently biasing the latter in a direction away fromthe first limiting position thereof toward the second limiting positionwith a spring force, which increases as the pivot structure is displacedtoward the belt. The damping body has a relatively tight fit at itsinner periphery with the lower outer periphery of a core member 48 and arelatively loose fit between its exterior periphery and an interiorperiphery of the pivot structure. Angular displacement of the pivotstructure between its first and second limiting positions is accompaniedby a sliding movement between the exterior periphery of the damping bodyand the inner periphery of a mounting portion of the contacting surfacesvaries in accordance with the position of the pivot structure, theamount of friction likely varies as well and, hence, the torsional forcerequired to overcome the frictional force may also vary. Thus, the armadvantageously experiences a greater damping effect in a belt-releasingdirection.

[0008] Commonly assigned U.S. Pat. No. 6,206,797 to Quintus disclosesbelt tensioner configurations that create damping by increasing frictionbetween the spring bushing arm and spring case and between the armplatebushing, armplate and arm. The increase in friction is achieved byincreasing the axial load on the tensioner components using springs ordeflected armplates. While providing effective damping, thisconfiguration also increases the loads on critical wear areas that areessential to maintaining the alignment of the pulley. Accordingly, it isdesirable to have a structure which overcomes the above-discusseddrawbacks.

BRIEF SUMMARY OF THE INVENTION

[0009] It is therefore an object of the invention to provide a belttensioner with damping that is independent of the axial force of thetensioner.

[0010] It is another object of the invention to provide a belt tensionerwith a high level of damping while reducing the forces on critical wearareas.

[0011] It is still another object of the invention to provide a belttensioner having improved pulley alignment.

[0012] It is yet another object of the invention to provide a belttensioner having a longer tensioner life.

[0013] It is another object of the invention to improve assembly methodsof a belt tensioner to achieve proper level of damping by eliminatingprecise positioning of the arm plate.

[0014] The above objects are achieved in accordance with the inventionwherein a belt tensioner includes integral damping that is independentof the axial force on the tensioner. The damper consists of an arm and aspring steel armplate that has been formed in a cup shape. The edges ofthe cup-shaped armplate are modified to provide “fingers” which act assprings to provide force in a radial direction. A friction material isincluded between the fingers and the arm to form a contact area whichincreases friction between the arm and the armplate thus producingdamping. The friction material is characterized, in an exemplaryembodiment, as a polymeric material; however, it is within the scope ofthe invention to utilize suitable alternative materials, or combinationsof materials or components, which exhibit characteristics effective toincrease friction between the arm and the armplate of the presentinvention. In accordance with the invention, the friction material maybe co-molded onto either the inner or outer portion of the cuppedarmplate. If the friction material is co-molded onto the cuppedarmplate, it may also include a provision to seal the tensioner toprevent contamination from entering the damping cavity of the belttensioner.

[0015] The armplate is keyed to a pivot means of the tensioner toprevent rotation of the armplate and provide relative movement betweenthe friction material and the arm. Since the damping force isindependent of the axial force needed to hold the tensioner assemblytogether, bushings disposed in the tensioner to keep the arm alignedwill wear less, increasing the life of the tensioner. Methods ofassembling the tensioner of the present invention are also improvedbecause precise positioning of the armplate to achieve proper level ofdamping is eliminated.

[0016] According to the invention, the above-described belt tensionerallows a high level of integral damping while reducing the forces oncritical wear areas providing improved pulley alignment and longertensioner life.

BRIEF DISCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a top plane view of the belt tensioner having integraldamping of the present invention;

[0018]FIG. 2 is a cross-sectional view taken through line 2-2 of thebelt tensioner of FIG. 1; and

[0019]FIG. 3 is a perspective, exploded view of the belt tensioner ofFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring now to the drawings, FIG. 1 illustrates a belttensioner in accordance with the invention wherein the belt tensioner 10includes a lever arm 12 having a plurality of stops 14 which extendradially outward from the outer periphery 16 of the lever arm 12 tolimit the rotation of the arm 12, a housing 18 into which the lever arm12 is disposed, tensioner armplate (damper) 20 having a plurality offinger elements 22 extending from the peripheral edge of the armplate 20to provide a spring force in a radial direction, and a locking member 24for securing the armplate 20 to the housing 18. The lever arm 12 furtherincludes a support member 26 fixedly attached to and extending outwardlyfrom the lever arm 12 for accepting and supporting a pulley assembly 28(FIG. 3) which includes a pulley 30, a mounting bolt or pin 32 and amounting aperture 34 into which the mounting bolt or pin 32 is connectedto secure the pulley 30 to the support member 26.

[0021] As shown in FIGS. 2 and 3, the belt tensioner comprises:

[0022] a pivot shaft 42 extending along a longitudinal axis and formedwith an outer axial end 44;

[0023] a housing 46 having a horizontal bottom 48 and a circumferentialwall 50 extending vertically from the horizontal bottom and having aninner circumferential wall surface 52 and an outer circumferential wallsurface 54. The housing is mounted and rotatably fixed on the pivotshaft 42;

[0024] a lever arm 12 mounted pivotally on the pivot shaft 42 and formedwith a distal end 56 and a tubular proximal end 58, the tubular proximalend extending into and operably connected to the housing 46;

[0025] a pivot bushing 60 having an inner circumferential wall surface62 and an outer circumferential wall surface 64 to aid in maintainingalignment of the lever arm 12, the pivot bushing 60 being axiallydisposed on the outer surface of the pivot shaft 42 such that said innercircumferential wall surface 62 is adjacent to an outer surface of asleeve 66 surrounding the pivot shaft 42 in housing 46 and extendingalong the longitudinal axis;

[0026] a spring element 68, preferably a steel coil spring, operativelyconnected to the housing 46 and to a lever arm 12 for pivoting the leverarm 12 about the longitudinal axis in a belt-tensioning direction;

[0027] a spring bushing 70 axially disposed between the spring element,68 and the lever arm 12, the spring bushing 70 having an outercircumference commensurate with the circumference of the outercircumferential surface of the vertical circumferential side wall 50 ofhousing 46, and an inner circumference commensurate with the outercircumferential wall 72 of said tubular proximal end 58 of said leverarm;

[0028] a pulley assembly 74 mounted on the distal end of the lever arm12 for receiving an endless drive belt (not shown) and applying atensioning force on the endless drive belt upon pivoting the lever armin a belt-tensioning direction, the distal end having the pulley mountedthereon being spaced axially apart from the upper end of said pivotshaft 42; and

[0029] an armplate assembly including a cup-shaped armplate 20, thearmplate 20 is preferably made of spring steel and is fixedly mounted onthe pivot shaft 42 to provide integral damping for tensioning an endlessdrive belt of a drive system, the armplate assembly comprises:

[0030] (a) an armplate having a cup-shaped cavity having acircumferential edge 78 and a plurality of spaced apart finger elements22 extending from said circumferential edge 78; and

[0031] (b) a friction material 80 disposed between the finger elements22 and on a surface of the armplate 20 for providing at least onecontact area having increased friction between the lever arm 12 and saidarmplate 20.

[0032] If desired, a suitable polymeric anti-friction tape 69, such as aTeflon tape, can be disposed between the coils of the spring 68 as isreadily known in the art.

[0033] The plurality of finger elements 22 extend generally upward andare configured to have one or more angular surfaces 36. Each of thefinger elements 22 act as a spring to provide a force in a radialdirection upon the side wall 38 of the armplate bushing 40. Armplatebushing 40 includes a cutout portion 41 which allows the armplatebushing 40 to easily fit into the damper cavity in the lever arm 12.Typically, the finger elements 22 are made of a rigid material which canprovide spring-like characteristics when the fingers are bent upward ina radial direction. The finger elements preferably contain more than oneangular surface which enhance the spring-like characteristics to producea more uniform and enduring pressure. The finger elements 22 of thearmplate 20, the side wall 38 and the armplate bushing 40 createsfriction while providing damping.

[0034] A friction material 80, such as a wear resistant plasticmaterial, is disposed between the finger elements 22 and the lever arm12. Exemplary wear resistant material include e.g., polyamides (PA);polyetherimides (PEI); polysulfones (PS); polyethersulfones (PES);polyoxymethylenes (POM), e.g., polyacetals; polyetheretherketones(PEEK); polyphenylene sulfides (PPS); polyphthalamides (PPA);polyphthalimides (PPI); and the like, or mixtures or blends thereof.Preferably, the friction material 80 is a polyamide such as nylons 6,nylon 4, nylon 9, nylon 11, nylon 12, nylon 66, nylon 610, nylon 611, ornylon 46. In a preferred embodiment of the invention the polyamidefriction material 80 is co-molded onto the armplate 20 wherein thefriction material 80 includes a sealing means such as a series oflabyrinths or flanges, or a portion of the armplate bushing 40 contactsthe lever arm 20 to form a seal to prevent contaminates from enteringthe damping cavity.

[0035] The pivot bushing 60 has one flared end which faces thehorizontal bottom 48 of housing 46. The pivot bushing 60 furthercontains a plurality of grooves 84, each of which extends thelongitudinal length of the pivot bushing 60. The pivot bushing 60 issecured to the horizontal bottom 48 of the housing 46 via acorresponding number of small notches located in the bottom inner cornerof each of the ribs 82 which protrude radially outward from the pivotshaft 66 on the bottom of the housing 46.

[0036] The pulley assembly 74 includes a pulley 30 containing a bearing86 such as a ball bearing and mounting means such as a mounting bolt orpin for mounting the pulley onto the pulley assembly 74 which is fixedlyattached to the distal end of lever arm 12. The outer peripheral surfaceof the pulley 30 comprises a plurality of protrusions 88 and recesses 90thereon, said plurality of protrusions 88 and recesses 90 extendingcircumferentially around said pulley 30. The protrusions and recessesmay be in the form of V-shaped projections and recesses, truncatedV-shaped projections and recesses or any other useful design.

[0037] While the above disclosure has described various embodiments, itis to be understood that the invention is not limited thereto, and issusceptible to numerous changes and modifications as known to thoseskilled in the art. Therefore, this invention is not limited to thedetails shown and described herein, and includes all such changes andmodifications as are encompassed by the scope and spirit of the appendedclaims.

What is claimed is:
 1. A belt tensioner with integral damping for use intensioning an endless drive belt of a drive system, said belt tensionercomprising: a housing including a pivot shaft extending along alongitudinal axis and formed with an outer axial end; a lever armmounted pivotally on said pivot shaft and formed with a distal end and atubular proximal end, said tubular proximal end extending into andoperably connected to said housing; a spring element operativelyconnected to said housing and to said lever arm for pivoting said leverarm about said longitudinal axis in a belt tensioning direction; anarmplate assembly including an armplate, said armplate being fixedlymounted on said pivot shaft to provide integral damping for tensioningan endless drive belt of a drive system, said armplate assemblycomprising: (a) an armplate having a cup-shaped cavity having acircumferential edge and a plurality of spaced apart finger elementsextending from said circumferential edge; and (b) a friction materialfor providing at least one contact area having increased frictionbetween said lever arm and said armplate; and a pulley assembly mountedon said distal end of said lever arm for receiving an endless drive beltand applying a tensioning force on said endless drive belt upon pivotingsaid lever arm in said belt tensioning direction, said distal end havingsaid pulley mounted thereon being spaced axially apart from said upperend of said shaft.
 2. The belt tensioner of claim 1 wherein said housinghas a horizontal bottom, a plurality of ridges adjacent said horizontalbottom, said ridges extending radially outward from said pivot shaft,and a circumferential wall extending vertical from said horizontalbottom, said circumferential wall having an inner circumferential wallsurface and an outer circumferential wall surface.
 3. The belt tensionerof claim 1 wherein said friction material is on at least one surface ofsaid armplate.
 4. The belt tensioner of claim 1 wherein said armplate ismade of spring steel.
 5. The belt tensioner of claim 1 wherein saidlever arm includes a damping cavity for accepting an armplate assembly.6. The belt tensioner of claim 1 wherein said plurality of spaced apartfinger elements extend angularly upward from said circumferential edge.7. The belt tensioner of claim 1 wherein said finger elements act assprings to provide force in a radial direction.
 8. The belt tensioner ofclaim 7 wherein said finger elements are configured to provide a highdegree of damping.
 9. The belt tensioner of claim 1 wherein saidfriction element is co-molded onto the armplate.
 10. The belt tensionerof claim 9 wherein said friction element includes sealing means toprevent contaminates from entering the damping cavity.
 11. The belttensioner of claim 1 further comprising a pivot bushing having an innercircumferential wall surface and an outer circumferential wall surfaceto aid in maintaining alignment of said lever arm, said pivot bushingbeing axially disposed on the outer surface of a pivot shaft such thatsaid inner circumferential wall surface is adjacent to an outer surfaceof said pivot shaft in said housing and extending along saidlongitudinal axis.
 12. The belt tensioner of claim 1 further comprisinga spring bushing axially disposed between said spring and said leverarm, said spring bushing having an outer circumference commensurate withthe circumference of said outer circumferential surface of said verticalcircumferential wall in said housing, and an inner circumferencecommensurate with the outer circumferential wall of said tubularproximal end of said lever arm.
 13. The belt tensioner of claim 1further comprising an armplate bushing disposed between said armplateand said lever arm to aid in maintaining alignment of said lever arm.14. The belt tensioner of claim 13 wherein said armplate bushing furtherincludes a cutout portion to allow the armplate bushing to tensionallyfit in the damper cavity.
 15. The belt tensioner of claim 1 wherein saidpulley has an outer peripheral surface, said peripheral surfaceincluding a plurality of alternating ridges and recesses extendingcircumferentially around said peripheral surface of said pulley.
 16. Thebelt tensioner of claim 1 wherein said pulley is operably connected to ahub on said distal end of said lever arm using a mounting meansextending through an axial opening in said pulley.
 17. The belttensioner of claim 16 wherein said mounting means includes a mountingbolt or mounting pin.
 18. The belt tensioner of claim 1 wherein saidspring element is a coil spring.
 19. The belt tensioner of claim 1wherein said spring element is made of steel.
 20. A belt tensioner withintegral damping for use in tensioning an endless drive belt of a drivesystem, said belt tensioner comprising: a housing including a pivotshaft extending along a longitudinal axis and formed with an outer axialend, said housing having a horizontal bottom and a circumferential wallextending vertical from said horizontal bottom, said circumferentialwall having an inner circumferential wall surface and an outercircumferential wall surface, said housing further including a pluralityof internal ridges extending radially outward from said pivot shaft; alever arm mounted pivotally on said pivot shaft and formed with a distalend and a tubular proximal end, said tubular proximal end extending intoand operably connected to said housing; a pivot bushing having an innercircumferential wall surface and an outer circumferential wall surfaceto aid in maintaining alignment of said lever arm, said pivot bushingbeing axially disposed on the outer surface of a pivot shaft such thatsaid inner circumferential wall surface is adjacent to an outer surfaceof a sheath surrounding said pivot shaft in said housing and extendingalong said longitudinal axis; a steel coil spring element operativelyconnected to said housing and to said lever arm for pivoting said leverarm about said longitudinal axis in a belt tensioning direction; aspring bushing axially disposed between said steel coil spring elementand said lever arm, said spring bushing having an outer circumferencecommensurate with the circumference of said outer circumferentialsurface of said vertical circumferential wall in said housing, and aninner circumference commensurate with the outer circumferential wall ofsaid tubular proximal end of said lever arm; an armplate assemblyfixedly mounted on said pivot shaft to provide integral damping fortensioning an endless drive belt of a drive system, said armplateassembly comprising: (a) an armplate having a cup-shaped cavity having acircumferential edge and a plurality of spaced apart finger elementsextending from said circumferential edge; and (b) a friction materialfor providing at least one contact area having increased frictionbetween said lever arm and said armplate; and a pulley assembly mountedon said distal end of said lever arm, said pulley assembly including apulley, wherein said pulley has an outer peripheral surface, said outerperipheral surface including a plurality of alternating ridges andrecesses extending circumferentially around said peripheral surface ofsaid pulley for receiving an endless drive belt and applying atensioning force on said endless drive belt upon pivoting said lever armin said belt tensioning direction, said distal end having said pulleymounted thereon being spaced axially apart from said upper end of saidshaft.
 21. The belt tensioner of claim 20 wherein said friction elementis co-molded onto said armplate and said friction element furtherincludes sealing means to prevent contamination from entering thedamping cavity.
 22. The belt tensioner of claim 21 wherein said sealingmeans is one or more labyrinths, one or more flanges, or one or moreportions of the armplate bushing in contact with the arm.
 23. A methodfor assembling a belt tensioner having integral damping, said methodcomprising: providing a housing including a pivot shaft, said pivotshaft extending along a longitudinal axis and formed with an outer axialend; providing a pivot bushing adjacent said pivot shaft in saidhousing; providing a coil spring element around said pivot shaft;providing an annular spring bushing axially disposed adjacent said coilspring element; providing a lever arm on said pivot shaft, said leverarm formed with a distal end and a tubular proximal end, said tubularproximal end extending into and operably connected to said housing;providing an armplate assembly comprising: (a) an armplate having acup-shaped cavity circumferential edge and a plurality of spaced apartfinger elements acting as springs and extending angularly upward fromsaid circumferential edge to provide force in a radial direction whereinsaid finger elements are configured to provide a high degree of damping;and (b) a friction material disposed between said plurality of spacedapart finger elements and said arm for providing at least one contactarea having increased friction between said lever arm and said armplate;and providing a pulley assembly on said distal end of said lever arm,said pulley assembly including a pulley, wherein said pulley has anouter peripheral surface, said outer peripheral surface including aplurality of alternating ridges and recesses extending circumferentiallyaround said peripheral surface of said pulley for receiving an endlessdrive belt and applying a tensioning force on said endless drive beltupon pivoting said lever arm in said belt tensioning direction; andassembly said housing, said pivot bushing, said coil spring, said springbushing, said lever arm, said armplate assembly and said pulley insequential steps to form a belt tensioner with integral damping.
 24. Themethod of claim 23 wherein said sequential steps comprises: (1)positioning said pivot bushing adjacent said pivot shaft in saidhousing; (2) positioning said coil spring around said pivot shaft insaid housing and coupling said coil spring to said housing; (3)positioning a spring bushing adjacent said positioned coil spring; (4)positioning said lever arm on said pivot shaft such that said tubularproximal end extends into said housing; (5) operably connecting saidarmplate assembly to said lever arm; and (6) mounting said pulleyassembly on said distal end of said lever arm.
 25. The method of claim24 wherein said housing has a horizontal bottom and a circumferentialwall extending vertical from said horizontal bottom, saidcircumferential wall having an inner circumferential wall surface and anouter circumferential wall surface, said housing further including aplurality of internal ridges extending radially on said horizontalbottom.
 26. The method of claim 24 wherein said pivot bushing furtherhas an outer circumferential wall surface to aid in maintainingalignment of said lever arm, said pivot bushing being axially disposedon the outer surface of said pivot shaft in said housing and extendingalong said longitudinal axis.
 27. The method of claim 24 wherein saidcoil spring element is operatively connected to said housing and to saidlever arm for pivoting said lever arm about said longitudinal axis in abelt tensioning direction.
 28. The method of claim 24 wherein saidannular spring bushing is positioned between said coil spring elementand said lever arm, said annular spring bushing having an outercircumference commensurate with the circumference of said outercircumferential surface of said vertical circumferential wall in saidhousing, and an inner circumference commensurate with the outercircumferential wall of said tubular proximal end of said lever arm. 29.The method of claim 24 wherein said lever arm includes a damping cavityfor accepting an armplate assembly.
 30. The method of claim 29 whereinsaid armplate assembly is mounted on said pivot shaft to provide andendless drive belt of a drive system with integral damping, saidarmplate assembly including a cup-shaped spring steel armplate and afriction material having an aperture therein disposed between saidarmplate and said lever arm.
 31. The method of claim 24 wherein saidfriction element is provided between said finger elements and said leverarm by co-molding a friction material onto said armplate, said frictionelement further includes sealing means to prevent contamination fromentering the damping cavity.
 32. The method of claim 24 wherein saidpulley assembly is operably connected to a hub on said distal end ofsaid lever arm using a mounting bolt extending through an axial openingin said pulley, said pulley being spaced axially apart from said upperend of said shaft.
 33. The method of claim 24 wherein said sequentialstep 5 includes positioning said armplate assembly into said dampingcavity and onto said pivot shaft, said armplate assembly including acup-shape spring steel armplate and a friction material having anaperture therein disposed between said armplate said lever arm to aid inmaintaining alignment of said lever arm, said armplate assemblycomprising: (a) an armplate having a cup-shaped cavity having acircumferential edge and a plurality of spaced apart finger elementsacting as springs and extending angular upward from said circumferentialedge to provide force in a radial direction wherein said finger elementsare configured to provide a high degree of damping in one; and (b) afriction material between said plurality of spaced apart finger elementsand said arm for providing at least one contact area having increasedfriction between said lever arm and said armplate.
 34. The method ofclaim 23 wherein said armplate friction element is co-molded onto saidarmplate, said friction element further including sealing means toprevent contamination from entering the damping cavity.
 35. The methodof claim 33 wherein said sealing means is one or more labyrinths, one ormore flanges, or one or more portions of the armplate bushing in contactwith the arm.